Bobbi Kristina Brown case: What we know and don't know

(CNN) -- Three years ago this week, singer Whitney Houston was found dead In a bathtub at a Los Angeles-area hotel.

Now, her only child, Bobbi Kristina Brown, is in a medically induced coma after she was found unresponsive in her suburban Atlanta townhouse -- also in a bathtub.

Houston's death was ruled an accidental drowning. But many questions remain about what happened to Brown.

The family isn't saying much. Neither are police, though they've said they're treating Brown's case as a criminal investigation.

Though little concrete information has surfaced, rampant rumors certainly have. The speculation prompted Brown's family to admonish some media outlets, saying "the desire to be 'first' has clouded the judgment of many reporters."

So here is what we know, and don't know, about the case:

Brown's condition

What we know:

She's in a medically induced coma. Early last week, sources close to the family said she opened her eyes briefly and suffered seizures.

What we don't know:

The extent of her injuries. We also don't know what prompted doctors to induce her coma, or what the reported seizures and eye-opening mean.

The boyfriend

What we know:

Nick Gordon was one of the two people who reportedly found Bobbi Kristina Brown unresponsive in the tub. Brown called the 25-year-old her husband, but her father's attorney said the two were never married.

Gordon was taken in -- but not formally adopted -- by Houston when he was 12 years old.

A family friend says he's not welcome in Brown's hospital room.

What we don't know:

Why Brown called Gordon her husband when she didn't appear to be legally married.

In January 2014, she tweeted a picture of wedding rings, along with the words, "#HappilyMarried• SO#Inlove."

"GoodAmbreakfast for MYHusband," Brown also tweeted. "Surprise baby! Heh my man is the best :)(: so he deserves the best:) @nickdgordon."

The couple's friend Daphne Barak said she believes Gordon and Brown were very much in love.

"These two young people -- he was everything for her, she was everything for him," Barak told HLN's Nancy Grace.

The injuries

What we know:

Brown was found face down in her bathtub with unexplained injuries to her body, according to a source with knowledge of the investigation.

And police have questioned Gordon about bruises on Brown's chest, Barak said.

"Immediately, from the beginning, they asked him about injuries to the chest," Barak told Grace, adding that Brown is "very tiny."

What we don't know:

How Brown suffered those bruises. Barak said Gordon told her that the bruising stemmed from Gordon trying to perform CPR on Brown. Gordon couldn't be reached for comment.

The investigation

What we know:

Last week, police called the case a medical incident. But Tuesday night, the police chief in Roswell, Georgia, said detectives have launched a criminal investigation.

"I can confirm that we have a criminal investigation ongoing," Roswell Police Chief Rusty Grant said in an email to CNN.